This invention relates to railway braking apparatus of the type known as car retarders. More particularly the invention relates to a removable shoe structure and means for attaching the same to a car retarder.
Car retarders are generally employed along a railway track to retard the movement of passing railway cars. A commonly used type of car retarder employs brake beams disposed on opposite sides of the rail, running parallel to it. Wheel engaging shoes are mounted on the beams facing inwardly toward the rail. The shoes extend at least partially above the top of the rail so as to engage a passing car wheel. The shoes are elongated and spaced apart along at least a portion of their length so as to subject passing car wheels to a wedging force, thus slowing the car. This wedging force is often made variable in magnitude to accommodate different types of traffic. A representative example of a car retarder to which the invention can be applied is found in U.S. Pat. No. 2,273,481, issued to H. L. Bone on Feb. 17, 1942.
Because the shoes are subjected to extensive wear, recurrent replacement is necessary. Replaceable shoes have commonly been bolted to the brake beams using specially adapted bolts having relatively thin, round heads positioned off center on a straight shank. The bolt holes in the shoes are correspondingly counterbored with an offset so the bolt head will seat within the counterbore. The offset configuration serves to prevent rotation of the bolt during installation of the nut or the like and counterboring also serves to protect the head from wear. Counterboring each hole, however, is an expensive and time-consuming operation requiring several steps to prepare each hole in the shoe.
In conventional shoes in which counterboring is not performed, the bolt heads remain exposed to heavy wear. If the heads are lost, the shoe will loosen. Consequently, shoes must be more frequently replaced, negating any saving realized from elimination of counterboring.